Recently, researchers have started to propose and investigate approaches where information—such as topology, cost, or policies—provided by the underlying network layer can help reduce certain problems caused by application-layer traffic, such as a high volume of inter-ISP (Internet Service Provider) traffic because certain applications do not consider network layer locality. Given that a certain resource, e.g. some specific data or a chunk of a file, is available at several clients of a decentralized application, traffic flows can be optimized if a resource consumer, i.e. a client which would like to download a certain resource, can select among different resource providers in a way which is “better-than-random”. Application-Layer Traffic Optimization (ALTO™) is currently being developed as an IETF™ (Internet Engineering Task Force) standard for better-than-random resource provider selection by providing information regarding the underlying network. When operators are trying to localize data exchange between resource consumers and resource providers in order to save costs, e.g., using ALTO™ information, there is the risk to incur in a dangerous drawback, i.e., to “over-localize” the traffic preventing resource consumers from achieving an acceptable service quality, e.g., not receiving all data they need in the case of a live streaming application.
In the IETF™ ALTO™ working group, a protocol is being standardized for guiding applications, e.g., P2P (Peer-to-Peer) applications, so that they can perform “better-than-random” resource provider selection, see RFC 569, J. Seedorf, E. Burger: Application-Layer Traffic Optimization (ALTO™) Problem Statement (reference 1). Currently, many distributed applications, e.g. P2P applications, choose their peers to connect with more or less randomly. This creates high costs for ISPs because content which may be available close on the network layer topology is fetched from resource providers far away on the network layer topology.
With ALTO™, applications, e.g., P2P ones, can obtain information about candidate resource providers from an ALTO™ server, which is e.g. provided by the ISP of the application's user, to optimize resource provider selection. The kind of information that is meaningful to convey to applications via an out-of-band ALTO™ service is any information that applications cannot easily obtain themselves and that changes on a much longer time scale than the instantaneous information used for congestion control on the transport layer, see reference 1. Examples for such information are operator's policies, geographical location or network proximity, e.g., the topological distance between two peers, the transmission costs associated with sending/receiving a certain amount of data to/from a peer, or the remaining amount of traffic allowed by a peer's operator, e.g., in case of quotas or limited flat-rate pricing models.
Reference 1 describes the ALTO™ problem statement in detail. FIG. 1 shows a typical ALTO™ scenario (taken from reference 1). Note that in this figure the typical use case of ALTO™ with resource consumers and providers being peers in a P2P network is depicted.
The vision of ALTO™ is that ISPs and applications can achieve a win-win-situation where applications can maintain or even increase their performance while ISPs can reduce traffic transmission costs. One way for ISPs to achieve cost reduction through ALTO™ is through traffic localization: suggesting to resource consumers other resource providers through ALTO™ which are in the same ISP.
State-of-the-art solutions for ALTO™ provisioning suggest to feed the following kinds of information into an ALTO™ server:                operator's policies        geographical location information or network layer proximity        the transmission costs associated with sending/receiving a certain amount of data to/from a resource provider        
It is, however, an open research question how to adequately provision information into an ALTO™ server such that both ISPs and applications have a benefit. More specifically, the problem of achieving a win-win-situation between ISPs' goals and applications' requirements has not been considered in detail.
It is an object of the present invention to improve and further develop a method for operating a network and an according network for allowing a very effective traffic localization within ALTO™.